We will map the pathways of carbon and reducing hydrogen in the major energy linked pathways in the liver cell. The effects of hormones (e.g., glucagon, insulin, epinephrine) and of changing dietary regimes will be examined, with regard to localizing the major rate determining steps in the various pathways. Also the effect of glucose itself, as a signal rather than a metabolite, on control of liver metabolism will be further explored. We will use isotopic techniques and mathematical modeling, solved with the aid of a microcomputer. We are also attempting to quantitate the role of the peroxisomes in fatty acid metabolism, and to determine the direction of reducing hydrogen flux between the peroxisomes and cytosol, using specifically tritiated substrates.